.side_nav{
    position: fixed;
    top: 55px;
    left: 225px;
    width: 225px;
    margin-left: -225px;
    border-right: 1px solid #ddd;
    border-radius: 0;
    overflow-y: auto;
    bottom: 0;
    overflow-x: hidden;
    padding-bottom: 40px;
}